1. Field of the Invention
The invention relates to a metal-film forming apparatus and a metal-film forming method capable of suitably forming a metal film by applying voltage between an anode and substrate, and depositing metal from metal ions contained in a solid electrolyte membrane onto a surface of the substrate.
2. Description of Related Art
Conventionally, when manufacturing an electronic circuit substrate or the like, a nickel film is formed on a surface of a substrate in order to form a nickel circuit pattern. As film forming technology of such a metal film, technology that forms a metal film by a plating process such as a non-electrolytic plating process, or that forms a metal film by a PVD method such as sputtering, on a surface of a semiconductor substrate of Si or the like, for example, has been proposed.
However, when a plating process such as a non-electrolytic plating process is performed, rinsing after the plating process is necessary, and the resultant waste water must then be disposed of. Also, when a film is formed on a substrate surface by a PVD method such as sputtering, internal stress is generated in the metal-film coating, so there is a limit as to just how thick the film can be. In particular, with sputtering, the film is only able to be formed in a high vacuum.
In view of this, Japanese Patent Application Publication No. 2014-51701 (JP 2014-51701 A), for example, proposes a metal-film forming apparatus that includes at least an anode, a substrate that is a cathode, a solid electrolyte membrane arranged between the anode and the cathode, and a power supply portion that applies a voltage between the anode and the cathode. With this film forming apparatus, a storing portion that stores electrolytic solution (that is, an aqueous solution in which metal salt has been dissolved) that includes metal ions is provided between the anode and the solid electrolyte membrane so as to contact both the anode and the solid electrolyte membrane.
When forming a metal film on the surface of the substrate, the metal film made of metal from metal ions is formed on the surface of the substrate by applying a voltage between the anode and the cathode, and depositing metal ions contained in the solid electrolyte membrane on the cathode side (see JP 2014-51701 A, for example).